Convert Curves to Grease Pencil?
First convert your curves in to mesh objects, AltC > Mesh from Curve/Meta/Surf/Text.

Now just copy and paste the script below into blender's text editor, then with your object still selected press Run Script.

This script below will draw grease pencil strokes on the active object. 

import bpy
from mathutils import Vector

obj = bpy.context.object
mesh = obj.data
scene = bpy.context.scene

pencil = bpy.data.grease_pencil.new("pencil")
scene.grease_pencil = pencil

layer = pencil.layers.new("layer", set_active=True)
frame = layer.frames.new(scene.frame_current)

for edge in mesh.edges:
    stroke = frame.strokes.new()
    stroke.draw_mode = '3DSPACE'

    stroke.points.add(2)
    stroke.points[0].co = obj.matrix_world * Vector(mesh.vertices[edge.vertices[0]].co)
    stroke.points[1].co = obj.matrix_world * Vector(mesh.vertices[edge.vertices[1]].co)


Thanks to CoDEmanX for his making a grease pencil through bpy answer.